I am a limnologist and ecosystem ecologist who uses a combination of observational and modeling approaches to better understand the interactive effects of anthropogenic disturbance and global change on microbially mediated biogeochemical pathways in freshwater aquatic ecosystems. These biogeochemical transformations have ecosystem scale impacts and offer critical insights into the mechanisms behind ecosystem change. I use a multidisciplinary approach and place a large emphasis on collaboration and Team Science. 

Theme 1: Redox-based approaches to understanding ecological change in aquatic environments

Eutrophication, the deleterious growth of algae fueled by excessive nutrient additions, is one of the most pervasive anthropogenic disturbances in aquatic ecosystems. Research surrounding eutrophication has largely sought to understand the drivers and impacts of eutrophication through the lens of quantifying nutrient inputs. My research advances our understanding of eutrophication by moving beyond flux quantification and developing a robust understanding of the microbially mediated biogeochemical pathways which underpin these ecosystem scale changes. Using first principles of chemistry and our most foundational understandings of microbial physiology, my modeling work uses the underlying half reactions of microbial metabolisms to assess nitrogen cycling dynamics under varying environmental conditions. By using redox-constrained parameters (which may be more broadly applicable than species or location-specific parameters), my model improves our understanding of nitrogen cycling, and thus eutrophication, in environments where microbial community dynamics are largely unknown.

In the first research paper of my postdoctoral fellowship (in prep for ISME J), I show how this model identifies transition points of likely maximum nitrous oxide emissions as a function of organic matter loading. Nitrous oxide is a powerful greenhouse gas (with a greater warming effect than both carbon dioxide and methane). Thus, understanding conditions which promote nitrous oxide production is a critical component of understanding climate change that is currently poorly reflected in global ocean models. Furthermore, the contributions of industrial aquaculture to global nitrous oxide emissions are currently poorly quantified, leading to uncertainty in the climate impact of this growing industry.

Theme 2: Cryptic biogeochemical impacts of aquaculture

Organic matter (OM) loading is a ubiquitous effect of finfish aquaculture. One important ecological implication of OM loading is that it alters the biogeochemical transformations that dictate the degree to which bioavailable nitrogen is retained in an ecosystem as inorganic nitrogen or else converted to nitrous oxide or dinitrogen gas. Therefore, depending on surrounding ecosystem dynamics, an aquaculture operation may either 1) produce potent greenhouse gases, 2) induce eutrophication in surrounding waters, or 3) act as an ocean fertilization experiment, potentially sequestering carbon. The biogeochemical underpinnings of aquaculture’s impacts are poorly understood and even more poorly reflected in sustainability standards. As a faculty member, one of my group’s primary research goals will be to further understand the cryptic biogeochemical impacts of aquaculture. The goal of this research will be to improve the sustainability of the industry and also develop and test the ways in which aquaculture may expand our understanding of aquatic ecology while potentially providing a mitigation tool for climate change. These research aims are outlined in my recent publication (“The aquaculture industry as a global network of perturbation experiments”).

Theme 3: Biogeochemical cycling and trophic state development in warm water ecosystems 

Our understanding of tropical aquatic ecology and the key mechanisms behind regime shifts (such as eutrophication) lags behind that of temperate systems. My research works to correct this imbalance while advancing our broader understanding of aquatic ecosystem biogeochemistry. This body of research is largely grounded in my dissertation work which was focused on tropical lakes. One unique feature of many tropical lakes is the high temperatures (> 20 °C) of the anoxic water column in lakes which maintain stable seasonal stratification. These warm and anoxic conditions support anaerobic metabolisms that are otherwise thermally constrained at higher latitudes. I am particularly interested in how this unique thermophysical structure dictates the fate of anthropogenically sourced nutrients. This work is not only critical to understanding contemporary tropical lake ecology but offers insight into the ecosystem ecology of subtropical and mid-latitude lakes under future climate scenarios.